Effects of corrective surgery on natural history of atrial septal defect of secundum type.

Two hundred and seventy-eight patients with atrial septal defect of secundum type were operated on surgical closure of the defect. The patients were divided into 5 groups according to age at surgery, and preoperative complaints and laboratory findings were analyzed to evaluate natural history. As year passed, incidence of complaints increased. Cardiothoracic ratio (CTR), systolic pressure of the right ventricle (PRVS), end-diastolic pressure of the right ventricle (RVEDP), mean pressure of the right atrium (PRAm), ratio of pulmonary to systemic systolic pressure (PPA/PS), right ventricular dimension (RVD) and left atrial dimension (LAD) increased significantly, while frontal axis of the QRS complex, RV1, SV1 +RV5 and LVD decreased. No chronological changes were seen in ratio of pulmonary to systemic blood flow (QPA/QS) and ratio of pulmonary to systemic vascular resistance (RPA/RS). The first and second decades of life were considered to be stable stages of the disease. Postoperatively, changes in the above-mentioned parameters were compared in each age group, and effects of surgical repair on natural history were evaluated. Of 265 survivors, 168 were followed-up for more than one year, the longest period being 22 years. CTR, frontal axis, RV1, PRVS, RVEDP, PPA/PS and RVD decreased significantly, while SV1 + RV5, RPA/RS and LVD increased. No changes were seen in LAD. Surgical effects appeared most significantly in the first decade and least in the fifth or more. From these findings it would be concluded that corrective surgery should be best carried out in the first decade, at latest in the second, though not to be contraindicated by age alone. Otherwise, postoperative improvement of parameters delays or hemodynamical abnormalities may persist regardless of considerable clinical improvement.